PASVE® pH mounting and service valve for reliable and controlled pH measurement
PASVE® pH toimilaite PASVE® pH is a mounting and service valve of Satron Instruments Inc. for pH sensors which can be used with practically all pH and O2 sensors. In this way it has been possible to include the advantages and savings of the PASVE® product family also in pH measurements. PASVE® pH is a special two-position ball valve, to the ball of which the measurement sensor is fastened with a sensor-specific adapter.
- In the measurement position the sensor is protected from the main flow in an open protective pocket.
- In the service and calibration position the flow-through fluid channel mechanized on the body is in contact with the sensor’s tip but not with the process. A flushing water jet is directed straightly to the sensor end, which guarantees a good cleaning result.
The valve is opened and closed with a rotating movement of the ball, that is, the sensor is not pushed into the process against the pressure or possible process media. It eliminates the risk of the sensitive sensor tip getting broken when the sensor is connected to the process and allows reliable and durable special seals. Owing to the reliability of the PASVE® pH valve, flushing and calibration of the sensor can be successfully automatized and performed without interrupting the process.
There are three typical process-based problems, which damage or deteriorate pH sensors:
- high temperatures
- sensors becoming coated
- mechanical damages
In high temperatures the sensor is cooled by PASVE® pH’s flushing function. In addition, the operating life of the sensor is prolonged when using PASVE® pH, because the measurement is based on momentary and not on continuous measurement.
The sensor becoming coated is a physical process, where small spots from the pulp accumulate on the sensor’s surface. After the coating has started the sensor gets in a short time a covering layer of dirt to its surface. Regular water flushing prevents the fastening of the first dirt spot, and that is why the entire sensor remains clean. The entire sensor can get damaged or at least the measurement accuracy is reduced, when an effort is made to clean the fouled sensor tip with various treatments.
Mechanical damages directed to sensors are typical when tanks are cleaned. Water can be kept continuously in PASVE® pH’s fluid channel, which protects the sensor from getting damaged and drying out during cleaning or maintenance of the tank, without the measurement accuracy or response time becoming deteriorated.
PASVE® pH is a safe solution. The safety has been proven already in earlier PASVE® types, the construction of which corresponds to that of PASVE® pH. The detachment of the sensor in the measurement position is prevented. In addition, the manually-operated valve is equipped with locking of the operating position. Furthermore, the valve handle can be detached, without it the locking can neither be opened nor the valve turned. The valve equipped with a pneumatic or electric actuator can be connected to the control system and from there the customer-specificly designed backups of the operating position can be taken care of. If necessary, the actuator can be equipped with a springset, which returns the valve to a desired position when there is no operating pressure. It is not possible to move the valve by handpower. A double ball sealing to the outer air improves the safety of the operator.
Various design solutions, materials, actuators, limit switches and process connection options enable the suitability of PASVE® pH to almost all industrial processes.